So if you just did one or two journeys it would just charge you singles. Once you spend enough it automatically goes to a price of a travel card. So it really depends how much you use it and what zones you are going into and whether it is peak or off peak...

Generally speaking a peak travel card (zones 1- 2) is 7.20 and an off peak is 5.60 so you probably won't spend more than that.

to get a one day travelcard which gives me unlimited travel in all zones plus a return to Twyford for £10.50. However I feel like such a chode with my paper ticket. I used to live in London! Am not a tourist! Don't look at meeee!